The present invention relates to the handling of digitally signed and/or encrypted message data, and more specifically to the policy based expiry of digitally signed and/or encrypted message data by a messaging provider.
Message data may be digitally signed using a digital signature. Such digital signatures typically have an expiry time after which they become invalid. Similarly, message data may be encrypted using a symmetric key. Such symmetric keys typically also have an expiry time after which they become inadequate. When a message consumer receiving such a signed or encrypted message tries to authenticate the message or to decrypt the message, it will find that the digital signature or the symmetric key has expired, meaning that it is not able to authenticate or to decrypt the message. The authentication or decryption by the message consumer of a message requires significant processing power and time, which is then wasted because the message cannot be authenticated or decrypted by the consumer of the message.
Expiry messages contain a period of time, for which they are valid, set by an application that puts the message onto a queue. The expiry time is a field in the message descriptor of a message which gets decremented as the message spends time on a queue. When a message is retrieved by a message consumer, prior to expiration, the expiry time represents the amount of time left from the original time specified. When a message's expiry time has elapsed, it becomes eligible for discard by the queue manager. The message is discarded when a browse or nonbrowse retrieve occurs on the message.
The concept of message expiry is already an established mechanism in the field of messaging. For example, in the IBM® WebSphere® MQ® product, a message producer can request that a message should cease to be valid after a set period of time. Policy based signed digital messaging is also an established technology as implemented by IBM WebSphere MQ Advanced Message Security. Error handling is implemented by the message consumer and is not an integral part of the messaging engine.
U.S. Pat. No. 8,769,492 B2 discloses that a message transfer agent scans stored messages to determine whether or not the content has expired. If the content has indeed expired the administrator may take steps to have the expired content deleted entirely, refreshed with more current content, or replace with a tombstone indicating that the original content has expired. The message sender elects to apply rights management protection to the message at the time of sending.